In today's disk storage technology, there is great demand for fast data transfer rates and high memory capacity/density. All disk drive subsystems (DD) are designed to tolerate inconsistencies in media coating (defects), otherwise loss of data or increased response time would result. In order to mask the effect of small defects in media coating, one must locate these small defects and direct the DD subsystem to skip over them ("skip assignment"). Many passes of Write/Read test with various number of test patterns are required in order to locate defects and "assign" them, so that the defective areas of a disk will not be accessed during normal user operations.
It would take many days of test time to locate all the defects on a disk surface. Thus, a special "analog media tester" can be used to locate and "assign" defects so those areas with insufficient magnetic readout will not be accessed during normal digital read/write operations (viz. a "media screener", or "head/media tester"). A related "digital tester" can also be used.
A disk drive "analog tester" can so test more area of a disc face at higher bit density than a "digital tester". "analog tester" hardware/software parameters can be adjusted to detect different sizes of media defects. The tighter these parameters, the smaller the (size of) the defects detected. "analog tester" parameters should be set tight enough to detect and assign most of the defects detectable during a user operation of a disk drive (cf. ensure that no more errors/defects will occur during normal operation of a disk subsystem than is promised). In order to make sure that the "analog tester" has detected all such defects, a "digital" test can be run via a host computer after the analog.
It is an object hereof to teach improved techniques for so "certifying" magnetic disk recording surfaces: e.g., techniques that may be used (e.g., see U.S. Pat. No. 3,633,187 re certification of tape) by manufacturers and users of disk storage subsystems to enhance data integrity and test process yield of disk subsystem.
It is a further object to so improve disk certification by and mapping magnetic disk media defects making the process more efficient, less expensive and briefer.